1. Field of the Invention
The present invention relates, in general, to methods and systems for cooling electronic components such as processors in servers and other computing devices, and, more particularly, to a design for fan modules configured to provide counter-rotating fans to provide increased static pressure while facilitating installation into and removal from a computer chassis (e.g., a server chassis/box or the like) and providing form factors useful for existing chassis and/or fan chambers.
2. Relevant Background
Removal of heat has become one of the most important challenges facing computer designers as failure to adequately cool devices can cause failure or operating problems. The rate of power dissipation from electronics components such as from processors (or CPUs) in high-performance server units continues to increase. In most cases, air cooling is used to remove heat from a heat generating surface of a CPU, a motherboard, and other components of the server or other computer/electronic product, with each chassis or box containing the heat generating components including one or more fans that draw air into the chassis or box to provide cooling and allow continued operation of the components.
For example, FIG. 1 illustrates a server (or other computer system) 100 that is designed to use forced-air cooling. The lid of the server chassis 110 is removed to show a motherboard with processors and other electronic components 120 that require cooling during operation of the server 100. The chassis 110 may be divided into two chambers with the motherboard 120 placed in one chamber of the chassis along with a number of fans 130 (in a fan chamber), with the fan chamber typically having a particular size and configuration (or form factor) that dictates the form factor of fans or fan modules 130 installed in the chassis 110. During operation of the server 100, the motherboard and other components 120 are cooled by redundant rows of fans 130 that are mounted to draw in cooling air 132 through a vented/open sidewall of the chassis 110 and eject the air 136 through another vented/open sidewall of the chassis 110 after it has been heated by the heat released from the motherboard and other components 120.
As shown schematically in FIG. 2, a cooling fan system 210 (e.g., as may be used to provide the fans 130 of FIG. 1 or the like) may be provided in a chamber in two or more fan trays 220, 230. The cooling fans 224, 234 may be provided in pairs within a number of modules 222, 232 with the fans 224, 234 positioned in two or more rows for redundancy (e.g., behind the front wall or bezel of the chassis). The fan modules 222, 232 may, of course, vary in configuration to provide cooling with one typical fan module being populated with or including a pair of 40 mm, 15000 RPM fans and with a chamber 210 typically including at least 4 but typically 6 or more modules 222, 232 (or 8 to 12 or more fans 224, 234 per server or computer product). The modules 222, 232 as well as the included fans 224, 234 are typically hot swappable with each fan module including an LED fault indicator to facilitate maintenance or replacement. The fans 224, 234 are accessible in many chassis designs from a hinged hatch door in the side of the server chassis or over the fan chamber 210. This arrangement makes it possible to access the fan modules 222, 232 without interrupting system operation, with maintenance or swapping typically involving removing one or more of the fan modules 222, 232 and inserting a new or a repaired module in its place. Hence, it is typically preferable that the modules 222, 232 be of an interchangeable design allowing one module to be removed and another to be installed without concern of improper installation and/or operation (e.g., a fan positioned with incorrect airflow direction or the like).
An ongoing challenge for the design of cooling fans and fan modules is providing adequate airflow through a computer chassis. As the performance of computer systems increases, so does the amount of heat generated by various system components. Effective system cooling requires careful management of airflow, and, due to the increased heat or thermal output of chassis components, more airflow is required to achieve effective cooling. Computer chassis are more often being designed with high density of components that creates high impedance bottlenecks where cooling airflow is restricted or nearly blocked. As a result, effective cooling of these systems requires fans or fan modules that can achieve or provide high static pressure to overcome the restrictions and pressure drop within the chassis. Arranging two rows of fan modules as shown in FIGS. 1 and 2 is mainly provided to provide redundancy but it does increase the achieved static pressure to provide two adjacent fans.
Unfortunately, existing fan modules are typically arranged with pairs of fans in adjacent rows operating or rotating in the same direction (e.g., both fans rotate in a clockwise or counterclockwise direction), and such an arrangement does not double the static pressure and often does not increase static pressure sufficiently to provide a desired cooling airflow through the high impedance chassis or computer components. Some work has been done to provide counter-rotating fans to increase static pressure. For example, custom designed cooling fans have been produced with a single housing or module that includes two fans with a shared central axis that rotate in opposite or counter directions (i.e., a counter-rotating fan assembly or counter-rotating flow). These fans provide higher static pressures, but their housings present a different and incompatible form factor than generally found in fan chambers of existing chassis, e.g., do not present side-by-side pairs of fans. Further, these fans do not properly support redundancy as failure often causes a portion of a chassis to not be cooled, in contrast to the designs of FIGS. 1 and 2 where a single fan or module failure does not end airflow but only reduces it.
Hence, there remains a need for enhanced fan module designs that provide fan arrangements with higher static pressure to provide increased airflow through a computer chassis. Preferably, such fan module designs would also facilitate installation of the fan modules within a chassis fan tray or deck without requiring modifications to the chassis or fan chamber (e.g., with the same or similar form factor as existing fan modules).